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SAA7385 Datasheet, PDF (22/64 Pages) NXP Semiconductors – Error correction and host interface IC for CD-ROM SEQUOIA
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Philips Semiconductors
Error correction and host interface IC for
CD-ROM (SEQUOIA)
Preliminary specification
SAA7385
Table 12 Microcontroller address page register: 0xF0FF
MNEMONIC R/W
7
PAGEREG R/W
−
DATA BYTE
6
5
4
3
−
PAGE_EN(1) MA_19 MA_18
Note
1. PAGE_EN is disconnected.
2
MA_17
1
MA_16
0
MA_15
Register 0xF0FF is used by the buffer manager for the upper address lines when the microcontroller addresses
non-frame memory. These registers overlap frame memory, so register 0xF0FF must be programmed with an address
in the top part of the memory if no overlap is required. The microcontroller page address line is selected from this register.
The outputs are used directly to control DRAM access cycles, and will affect any current DRAM cycle in progress.
It is possible to access three contiguous frames from the microcontroller by reading the three data sector windows,
0x8000 to 0x8FFF, 0x9000 to 0x9FFF and 0xA000 to 0xAFFF. This function is required for the decoding of the sub-code
information. If the ‘next’ frame wraps past the last frame pointer (LASTFRM) then the pointers are modified to wrap back
to the start pointer onwards (FEFRM#); this section is transparent to the microcontroller.
Table 13 Program memory control register: 0xF09F
DATA BYTE
MNEMONIC R/W
7
6
5
4
3
2
1
0
PRGMEM R/W DATAPRG EN_WIN SEL_TOP INV_A15
−
−
−
−
Register 0xF09F controls a system test feature where an SRAM is used for the 80C32 external program memory;
note DATAPRG must be set for any of these features to be enabled.
Table 14 PRGMEM field descriptions
FIELD
INV_A15
SEL_TOP
EN_WIN
DATAPRG
LOGIC
DESCRIPTION
0 normal operation
1 invert A(15) to program memory for data memory access
0 select bottom 32 kbyte window
1 select top 32 kbyte window
0 windowing disabled
1 32 kbyte windows are enabled and SEL_TOP is used to determine window selected
0 normal operation
1 data memory is mapped to program memory and data memory DRAM accesses are
disabled
1996 Jun 19
22
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